Patent Document 1 discloses a scrap shearing machine of this kind for handling scrap in the form of cylindrical containers and pipes of large-diameter, in which the scrap is squashed from the side to reduce its width and then sheared into short pieces by means of a guillotine-type straight-blade shear-stand.
Patent Document 1: U.S. Pat. No. 3,945,315
This known scrap shearing machine uses an open feed channel which is wider than the mouth of the shears. On one of sideways along a longitudinal direction of the feed channel, there is provided a side hydraulic ram for squashing the scrap sideways to reduce its width before feeding it into the comparatively narrow mouth of the shears. The side hydraulic ram comprises a main ram and an auxiliary ram. The auxiliary ram can be operated in advance independently of the main ram. The working face of the auxiliary ram is situated adjacent to the mouth of the shears and is shorter than the working face of the main ram in the feed channel. Therefore, with respect to the longitudinal direction of the feed channel, the sum of lengths of the working faces of the auxiliary ram and the main ram corresponds to the full length of the box-shaped feed channel. The scrap shearing machine also comprises a down thrust plate provided in a pivoted manner which covers the full length of the channel along a sidewall of the channel on one side to which the side hydraulic ram is opposed. The down thrust plate is driven by a hydraulic cylinder which is pivoted by a pin on an arm fixed to the machine frame at the one side for holding down the scrap to prevent it from bulging upward along the full length of the channel before the scrap enters the mouth of the shears.
With such a conventional scrap shearing machine, in order to shear, into short scrap pieces, a relatively large, long, and rigid metal scrap, for example, discarded land vehicles such as railroad coaches including a freight car and a passenger car, large-sized automobiles including a limousine and a heavy-duty truck or architectural scrap including section steels, the box-shaped feed channel also must be constructed to have a suitably long, wide and deep dimension for being able to handle such a large-long metal scrap. In order to squash a rigid metal scrap occupying almost all the length of such a long, wide and deep feed channel by the downward thrust plate and side hydraulic ram comprising the main ram and the auxiliary ram covering the full length of the feed channel, there is required an extremely powerful hydraulic cylinder for driving each of the rams and thrust plate.